How to fight slugs and liverwort in Oregon: Ask an expert

The crocus are up, buds are about to burst. Spring is on its way. Got a question? Get answers from Ask an Expert, an online question-and-answer tool from Oregon State University’s Extension Service. OSU Extension faculty and Master Gardeners reply to queries within two business days, usually less. To ask a question, simply go to the OSU Extension website and type in a question and the county where you live. Here are some questions asked by other gardeners. What’s yours?

How to fight slugs?

Q: Is there a definitive answer to our slug problem? What is the most efficacious method of removing these dratted pests.

– Multnomah County

ask an expert

courtesy of OSU Extension Service

A: There is no definitive “cure” for slugs. They like our environment and have probably been here since before humans. However, there are some methods you can use to reduce their populations, and damage to your plants. Although this (rather long) Extension article doesn’t have pictures, you undoubtedly already know what they look like. But I’ve attached a photo of slugs “bellying up to the bar” for their favorite drink: beer. But iron phosphate (sold as Sluggo) is effective. (Note that Sluggo Plus has additional chemicals that are not necessary for the control of this mollusk.)

– Kris LaMar, OSU Extension Master Gardener

What's this weed?

Q: What is the weed shown in this photo and how can we get rid of it? We believe it arrived with some compost. It spreads very fast. Will spraying or tilling it under kill it? – Multnomah County

ask an expert

Courtesy of OSU Extension Service

A: This plant is liverwort, which is a moss-like plant that spreads by spores. It is a common weed in nursery pots, so it might have arrived at your site that way.

Liverworts are difficult to control and are resistant to most herbicides.

Your best bet for management is to scrape the plant out of the area where it is growing and change the conditions that favor its growth (exposed, wet soil with a lot of nutrients). It might take several rounds of scraping over two to three months to totally remove the liverwort.

If this is a lawn area, you might scrape the liverwort off the areas where it is growing and reseed the bare soil so that a vigorous stand of turf can take root and out compete the liverwort. If this is a landscape area, letting the soil dry out this summer could help.